1. Field
The present disclosure relates to a light source device that uses two lenses.
2. Description of the Related Art
A small-sized light source module that uses a light source such as a semiconductor laser has to have a thin thickness for use as a light source device for a projector. Thus, the small-sized light source module is restricted to a light source module whose lens size is small. Thus, because the lens has to be arranged close to a light emission point of the semiconductor laser, high precision such as 10 μm to several μm is requested for an allowable offset of the distance between the light emission point of the semiconductor laser and the lens.
International Publication No. WO2016/002267 Pamphlet (laid open on Jan. 7, 2016) discloses a method in which a lens is spatially adjusted and fixed by using an adhesive such as a thermosetting resin or a UV curing resin in an optical module that uses such a small-sized lens.
However, in such an above lens fixing method, the lens is fixed after position adjustment in each direction of three dimensions. Thus, even in a case where an adhesive is applied for fixing for any direction of X axis, Y axis, and Z axis, an influence of curing shrinkage of the adhesive on the fixing position in the other direction may not be avoided. Accordingly, there is a problem in that the lens moves in adhesion.
Due to such a problem, when the lens is adhered after optical axis adjustment and beam spot size adjustment are performed, the lens is offset due to the curing shrinkage of the adhesive. In addition, this problem especially occurs in a high temperature action. Because the lens is offset because an adhesive portion for fixing the lens to a housing swells due to a high temperature, the optical axis of the laser changes in accordance with the temperature. Consequently, in a case where the light source device is incorporated in a projector or the like, there is a concern that a projected image becomes hazy or blurry due to relative offsets of optical axes of plural lasers. Further, presently, there is a strong demand for a light source device that is small-sized and further has optical characteristics of convergence and divergence, which are difficult to realize by one lens, in the market. Further, there is a strong demand for reliability of the capability of a stable action at a high temperature.
It is desirable to provide a light source device that may reduce an influence of curing shrinkage of an adhesive, which occurs to any direction of three dimensions in adhesion fixing of a lens of a small-sized light source device and that may reduce an optical axis offset in a high temperature action.